1. Field of the Invention
The present invention relates to a seat recline mechanism that includes memory. After pivoting a vehicle seat back forward to allow a passenger to enter the back seat, the seat back returns to its original, adjusted orientation. The invention also blocks locking of the seat slide mechanism when the incline returns to a memory position. This invention also relates to a system implementing the recline mechanism in vehicles.
2. State of the Art
The seat backs of the front seats in most vehicles are adjustable. The adjustment allows a person in the front seat to adjust the incline of the seat back to conform to the person's comfort. Many seats also recline back to allow one to recline.
When passengers enter the rear seat of a two-door vehicle, they must pivot the front seat forward. This is called "dumping" the front seat. Most seats have an adjustment mechanism that adjusts the seat back angle to account for the seat occupant's comfort or for reclining the seat. Many seats dump merely by releasing the seat's adjusting mechanism. Therefore, after the passenger enters the back seat, returning the seat back to the upright position just readjusts the seat back. Unfortunately, that means that each time the seat is dumped, the front seat loses its subtle adjustment. Consequently, the user must readjust the seat every time a passenger enters a two-door vehicle past that seat.
For further ease for persons entering the rear seat, some vehicles seats slide forward when they are dumped. That sliding action gives the rear seat passenger more room to enter the vehicle.
Several devices separate dumping from normal adjustments and, therefore, do not lose their adjustment when they are dumped. Thus, after dumping, the seat back returns to its adjusted position that existed immediately before dumping. The following U.S. patents teach the concept of separation of dumping from other seat adjustments: Dinkel, U.S. Pat. No. 3,887,232 (1975); Tamura, U.S. Pat. No. 3,593,069 (1976), Kazaoka, U.S. Pat. No. 4,502,730 (1985), and Terada, U.S. Pat. No. 4,660,886 (1987). These devices are quite complex with many cooperating parts. Complexity adds to cost and the chance of failure. Adding more parts also increases the weight of the mechanism, which runs counter to weight reduction strategies favored by vehicle manufacturers.
In those systems where dumping and sliding occur, those two actions must be coordinated. Most vehicle seats are spring-biased forward. Therefore, when one adjusts the seat forward or backward by releasing the lock that prevent sliding, a spring biases the seat forward. That action works well for the dumping and sliding combined movement because the seat moves forward as it dumps. Also, spring force on most seats is greater than the spring bias force on the dumped seat back. Therefore, when the user returns the seat back to the upright position, the force he or she applies to the seat back often does not slide the seat backward until the seat back locks in an upright position.
When dumping and sliding work together, the system should lock the seat back and slide lock when the seat back returns to its memorized, upright orientation. After returning the seat back to its proper position, the entire seat either may lock too far forward or may not lock. If the seat is not locked from sliding, the seat's occupant may not know that fact. Consequently, in a sudden stop, the unlocked seat may move forward to carry the occupant with the seat. If, instead, the slide locks the seat too far forward, the user must release the slide lock and position the seat to a comfortable position. Having to readjust the seat position make memory for the seat back less attractive. If the seat locks forward, the user will have to make some adjustment to the seat every time the seat dumps.